Ergodic divertor effect on low-Z impurity transport for inner-wall limited plasmas in Tore Supra

Observations of systematic spatial modulation of low- Z impurity radiative emissions are analysed for Tore Supra ergodic divertor discharges limited on the inner wall. Some similarities to modulations previously observed with Marfe-like conditions are observed, but significant differences are also seen in the cases studied here. A simulation of the modulations is made, using the three-dimensional edge transport code BBQ. The simulations suggest that an important role is played by charge exchange with neutral deuterium, in addition to the ergodic divertor-induced modulations of the electron temperature. The interpretation highlights the important role of intermediate- Z states in impurity transport processes.